The response of LuxS/AI-2 quorum sensing in Lactobacillus fermentum 2-1 to changes in environmental growth conditions

Quorum sensing (QS) is a communication mechanism based on the production of autoinducers in order to regulate cooperative behavior and physiological traits among bacteria. Autoinducer-2 (AI-2) is mediated by luxS and pfs genes and is used for both intra- and interspecies communication. The effects of environmental stresses, such as pH, temperature, osmotic, and nutrient stresses, were investigated on the LuxS/AI-2 QS system in Lactobacillus fermentum 2-1. The AI-2 activity in L. fermentum 2-1 was induced by stress responses to acid shock, high temperature, and nutrient inadequacy while a decrease in activity was correlated with high pH, low temperature, and osmotic stress. Maximum transcription of luxS and pfs was achieved after L. fermentum 2-1 was exposed to acid shock, low temperature, high concentration of NaCl, and diluted MRS broth. The results indicate that various stresses affected the LuxS/AI-2 QS system, which may be involved in the resistance process of the L. fermentum 2-1.